Jupiter’s four largest moons were the first moons to be discovered orbiting another planet. They are incredible worlds of volcanoes, craters and hidden oceans that have barely been explored. Some could be home to alien life!
Io
Io is similar in size to the Earth’s moon. Chemicals from volcanic eruptions have turned its surface yellow-orange. Io is the most volcanically active world in our Solar System. Hundreds of volcanoes spew lava thousands of metres into the air.
Europa
Europa is the smallest of Jupiter’s four largest moons. On the surface there is water ice and underneath scientists believe there is an ocean! Gigantic jets of water are thought to spout from geysers on Europa’s icy surface. These fountains may be up to 20 times higher than Mount Everest!
Ganymede
The largest moon in our Solar System, Ganymede is even bigger than the planet Mercury! It is made of rock and ice.
Callisto
This battered moon has more craters than any other object in the whole Solar System!
In the night sky
If you look at Jupiter through a telescope you might see bright lights hovering next to the planet. These are actually its four largest moons!
Jupiter’s four largest moons are known as the Galilean moons, after the Italian scientist Galileo Galilei, who discovered them in 1610.
In orbit
With at least 67 moons, Jupiter is almost like its own mini Solar System. Io is the closest of the four largest moons and takes 42 hours to orbit around the planet. Callisto, the furthest away, takes around seventeen days to complete its orbit.
Picture Credit : Google